Gain Setting Tutorial

[DIGIDIGIBOMBO 10+ year member]

Hi there, i have a question again.First to set the HU max level i must use ordinary music and when i hear distortion i lower a bit, or i must use a test tone cd?:STo set the amp gain, i put a regular music cd and pick all the bass, frequencies of lpf, hpf...that i want ok. After this i use the voltage calculations and start increasing the gain while listening to the test tone cd till i have the right voltage, thats it??? I cannot do this with a regular music cd? it must be a test tone?? for a sub i use 45Hz, and for 6x9" 40rms speakers i use 1Khz? I have a built in cross over in the amp so i must set it before setting the voltage stuff right? U said also, that if we have an external cross over we must set it at last, y?? u mean it wont affect the voltage after setting the gain? Thankssssssss a lot , sorry to many questions i know The test tone cd for a sub, must be 45 Hz at 0dB?

 

[Colin P 10+ year member]

ok guys,

I have two amps,

1)Diamond Audio D5300.4 Bridged so I believe its 2x125w @ 4Ohms = 22.36v for each of the two channels?

2)Soundstrea, Van Gogh 1600.2 bridged so 1600w x 1 @ 4Ohms = 80v

Also, I see that it's reccomended that you unhook the rca's for teh other amp right? well, teh soundtream ampp is ran off the diamond one so can I just unplug the components or should I pull the RCA's out of the diamond amp and plug them in the soundstream amp and then switch them back when I have done the sub amp?

if you need to know I have Diamond Audio S600S Components and a single Diamond Audio TDX 12''D4

Headunit is an old Pioneer DEH P 6400 (about four years old) until I install the car pc.

 

[DIGIDIGIBOMBO 10+ year member]

Hi, i would like to know y do we use a 1Khz at 0dB test tone for testing the speakers, and 45Hz at 0dB for the sub. Is it cause the 1Khz is maximum the frequency that will out out me the most power from amp to speakers? same thing for the subs ( 45 Hz)?? when i want to set the HU volume, i use the 1Khz test tone, and i should be disconecting the sub while doing this?

i have a 50rms per channel amp, i am bridging it to use a 300 rms sub at 4ohms, so i must have 28.284Volts at a test tone of 45Hz? and 2 speakers 40rms each and 4 ohms to the remaining 2 chanels would be 12.69each chanel at a 1Khz test tone? i am using the leat rms power in the formula weither the amp or speaker( if i have a 50rms amp chanel with 40rms speaker, i am using the 40rms as being the power that i want to output).

thx a lot guys

 

[Colin P 10+ year member]

Hi again, i have a 200 watts rms/4channels amp, so 50rms watts for each channel. I was going to use a 300 wats rms sub( i will bridge it) + 4 speeakers 6x9" 40rms each. The amp is a 2ohms stable, so i told some guys i will also connect the 4 speakers( each channels with 2 speakers in parallel), thay told me its too much for the amp to support. Y is that??? When we bridge a sub, we cannot use parallele wiring with the other channels??if i buy a 2 channels 50watts rms each amp, can i connect to it the speakers( 40 rms each) usinf parallele connection??? ( 2 speakers for each channel) thanks a lot guys

what does that have to do with setting gains?

 

[DBfan187 5,000+ posts]

thoughts on this

 

[Posjr 10+ year member]

This my help alot of poeple.

http://www.angelfire.com/pa/baconbacon/page2.html

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[Colin P 10+ year member]

indeed, so my calculations were correct!

worked ok for the components but the sub was waaaaaaaaaaay too low, so cranked the gains on that one right back up

 

[IamDeMan 5,000+ posts]

OK I followed this guide to set the gains on the amp I am using in my wifes car (directed 1100d5). I got a few anamolies I would like to know if they are usual.

First thing I need to know is how to tell or know if a sine wave your are using is at 0db reference? I used a tone generator http://www.nch.com.au/tonegen/ to make my sine waves.

Next thing is why do they say to use 50 hz for the sub? I found that my amp made 8volts more on a 40hz tone. I am guessing it is because most music creates a prominent 50hz and less at 40hz. am I correct in assuming this? In any event I used the 40hz tone and figured that would make the setup that much safer.

Lastly I noticed that on my rear channel the left side made .5V less and on the front channel my right side made .8V less. Is this normal? shouldn't they be identical, or at least closer than that?

Lastly and this is why I ask about the 0DB reference, when I set them this way, my music was louder than when I just set them without a multimeter. What I did before the DMM was just play a loud bass cd and set the sub gain until I got decent output, then I did the same with the mains but with a loud rock CD. I ask this question, because everyone else seems to be *****ing about how quieter it is after setting.

One other thing that isn't related to the gain setting is I am going into thermal shutdown after 20 or so minutes of full volume listening. This happened before setting it and now after setting it. It also happened with my Rockfords. After it shuts down I feel the amp and it is cooking. I think I may be getting bad voltage drops when playing loud. I will take my new DMM and confirm this then I will do the BIG 3 here soon and see if that rectifies that problem. If it isn't that, what should I look at next?

 

[IamDeMan 5,000+ posts]

The NCH Tone Generator does not make 0 dB tones ... even when you set it to 0 dB ...
Use Adobe Audition ...

Muchos Gracias! I had a suspicion this was true. Just didn't seem right that my music was still loud as fvck!
EDIT: Holy hell that software is $$$. No trial either. I don't think I will be buying that lol. I'll have to look for tones available for download, which I am having a hard time doing. No good freeware generators or at least trials?

 

[DIGIDIGIBOMBO 10+ year member]

Hi people, the voltage formula is the following: V=sqr( desired power x speaker resistance), i pick the smallest rms power between the amp and the sub right? if the amp has a 50 rms per channel and the speaker can support 70 rms i use the 50, and if the amp can output 70rms and speaker has a 40rms power i use the 40rms right? i have an amp that gives 50rms per channel at 4 ohms load, i want to bridge it to a 300 rms sub, i dont know what would be the power of the amp while bridged, a 50rms output per channel at 4 oms load doesnt mean it will be 100 rms per channel at 2 ohms load, sometimes its 60,70....they said nothing about it on the manual, what shall i do?? thx

 

[Decado 10+ year member]

Muchos Gracias! I had a suspicion this was true. Just didn't seem right that my music was still loud as fvck!
EDIT: Holy hell that software is $$$. No trial either. I don't think I will be buying that lol. I'll have to look for tones available for download, which I am having a hard time doing. No good freeware generators or at least trials?

Check out this thread man http://forums.caraudio.com/vb/showthread.php?t=108380 it has a few different places you can download test tones for free from.

 

[Decado 10+ year member]

WTF, that sux, i wish i would have noticed that. Lmao.

 

[Alpineinstaller 10+ year member]

the link is bad......

 

[hellbender 10+ year member]

anyone know why the jl audio gain tutorial link and site isnt working? I have a jbl px300.4 amp and the fronts are rated at 123 watts rms andi have a/d/s 236 is's for the fronts and i have the rear channels bridged for right now putting out 358 watts rms to an avalanche 15. I can get the sub voltage down ok but the highest voltage reading i get for the fronts is only like12.3 at vol. 30 with the treble set at +6 db. I have a panasonic cq401u cd player for now and if i turn up the volume past 30 then my tweeters go into protect mode. and even at 32 the voltage is only 15.6 . shouldnt my target voltage be like 21.9 for the fronts? I also have the cdt image enhancement kit which is an attenuater and an extra set of tweeters connected to my a/d/s tweeter output too. so if i go 120 watts x 4 sqrt = 21.9? even if i drop the ohms and use 120 x 3 sqrt = 18.97 still way shy of 12.3 volts. anything past like 31 on the vol. is met with distortion and my tweeters going into protect mode. please help i am way frustrated......thank you

 

[Decado 10+ year member]

Ok, so to get my rockford fosgate 601s to 600 rms@4 ohms bridged (49 volts) i have to set each gain (yes there are 2 gains) to 34.3. Anyone know why the left and right gains have to be at 34.3 to get 49 bridged? Shouldnt the left and right gains be 24.5?